1. Related Technical Fields
Related technical fields include road map data structures, for example, used in a navigation device. Related technical fields also include computer-readable data storage mediums and navigation devices that store and/or use road map data structures.
2. Description of the Related Art
Displaying a vehicle location and guiding a vehicle along a route to the destination by means of digital road map data is known. Generally, such road map data contains road network data at plural levels corresponding to the level of detail or the scale for the display of the road information. The road network data includes a plurality of links. Generally, link IDs (which identify the links) are sequentially provided in connection order along a link strings, in which each link has a common attribute. Link IDs structured to have a predetermined numerical range, which contains plural successive numbers is known. In Japanese Patent No. 3725022 and Japanese Patent Application Publication No. JP-A-2005-70482, a range proportional to each link length is set to the numerical range of the link ID.
In the road map data structure as described above, the link ID has a predetermined numerical range. When updating the road network data by dividing the existing link into plural sections for connecting a new link to the intermediate point of the existing link, the continuity of the link IDs sequentially arranged in the order of connection may be maintained. In the aforementioned case, the numerical range of the link ID of the existing link is divided to newly generate plural link IDs so as to be assigned to the respective divided sections of the that existing link.